What is the purpose of broker_timestamp_eye and broker_version_eye?

[njh]

Hello,

I have been going through fixing compiler warnings and found these unused variables? In Broker.c / main():

static char* broker_version_eye = NULL;
static char* broker_timestamp_eye = NULL;
broker_timestamp_eye = "RSMB_Timestamp " BUILD_TIMESTAMP;
broker_version_eye = "RSMB_Version " BROKER_VERSION; 

Is it used for some kind of symbol extraction/debugging voodoo?

nick.

[icraggs]

Not so complicated :-) To have a visible eyecatcher to locate timestamp/broker version in the binary.

[njh]

So it should stay then? 😀

Is there a way to make it as a known/special 'unused' variable?

This is what I see when compiling on Linux:

gcc -Wall -s -Os *.c -o broker
Broker.c: In function ‘main’:
Broker.c:252:15: warning: variable ‘broker_timestamp_eye’ set but not used [-Wunused-but-set-variable]
  static char* broker_timestamp_eye = NULL;
               ^
Broker.c:251:15: warning: variable ‘broker_version_eye’ set but not used [-Wunused-but-set-variable]
  static char* broker_version_eye = NULL;
               ^

The broker has the version in the console log:

njh@star:~/Projects/rsmb/rsmb/src$ ./broker 
20160621 155052.711 CWNAN9999I Really Small Message Broker
20160621 155052.711 CWNAN9998I Part of Project Mosquitto in Eclipse
(http://projects.eclipse.org/projects/technology.mosquitto)
20160621 155052.712 CWNAN0053I Version 1.3.0.2, Jun 21 2016 15:48:56
20160621 155052.712 CWNAN0054I Features included: bridge 
20160621 155052.713 CWNAN9993I Authors: Ian Craggs (icraggs@uk.ibm.com), Nicholas O'Leary
20160621 155052.713 CWNAN0075W Socket error 98 (Address already in use) in bind for socket 3
20160621 155052.713 CWNAN0078W Cannot bind port 1883
20160621 155052.713 CWNAN0015W Cannot start listener on port 1883
20160621 155052.713 CWNAN0016I MQTT protocol stopping
20160621 155052.714 CWNAN0044I Messages sent: 0
20160621 155052.714 CWNAN0043I Messages received: 0
20160621 155052.714 CWNAN0042I Uptime: 0 seconds
20160621 155052.714 CWNAN0055I Maximum heap use: 62896 bytes
20160621 155052.714 CWNAN0047I Broker stopped

Maybe add a --version command line option instead?

[icraggs]

I was asked to add the eyecatchers in the binary a long time ago. Some quick Googling came up with

attribute((unused))

to tell gcc to not produce the warning. (https://gcc.gnu.org/onlinedocs/gcc-3.2/gcc/Variable-Attributes.html)

[njh]

Will submit a PR that uses this:

#ifdef __GNUC__
  #define ATTR_UNUSED __attribute__((unused))
#else
  #define ATTR_UNUSED
#endif

[njh]

Fixed this as part of PR #22